Saturated hydrocarbons are obtained from petroleum, natural gas reservoirs, and other petroliferous deposits. They are, on a relative basis to other hydrocarbons, available in a relatively large supply. They have many uses in addition to being suitable as fuels. One of those uses, and one which has a high order of value in terms of uses, is as a raw material in chemical reactions when they can be made to react in an efficient, economical and predictable if not selective fashion. Particularly desirable is the ability to prepare terminally-substituted compounds, because terminally-substituted, or primary functional compounds, are in the greatest demand commercially. However, saturated hydrocarbons have strong C--H and C--C bonds which make the necessary reactions difficult for one or more reasons.
Various approaches to reaction of hydrocarbons have been studied over the years including thermal, chemical and photochemical. Examples of these are set forth in Janowicz and Bergman, J. Am. Chem. Soc. 105, 3929-3939 (1983). Most of these prior methods have consumed large amounts of energy in one form or another; and, importantly have lacked selectivity. Either, in addition to or separately, the prior methods have suffered other disadvantages.
Unsaturated compounds, in addition to being a valuable raw material for reactions which functionalized alkanes are not, do not always form terminally-substituted compounds but form 2-substituted derivatives according to Markovnikoff's rule.
Recently we found that certain organo-iridium complexes are capable of intermolecular oxidative addition to single C--H bonds in saturated hydrocarbons leading to hydridoalkyl iridium complexes which can be used to convert alkanes to alkyl halides. This is reported in Janowicz and Bergman, J.A.C.S. 104, 352 (1982). While this procedure enjoys a degree of benefits over the prior art it leaves room for improvement in several respects. One such important feature in the use of iridium complexes as precursors to alkyl halides is the need to pass through an organomercurial intermediate. The process using iridium also provides much less selectivity than theoretically possible and desirable.